1. Field of the Invention
The present invention generally relates to, a method for forming word line of semiconductor device, and more specifically, to a method for forming word line of semiconductor device wherein a lower portion of the word line on the channel region is a I-type and a upper portion of the word line is a line-type for improved characteristics, yield and reliability of the device.
2. Description of the Prior Art
FIG. 1 is a layout view of a conventional word line, and FIG. 2 is a cross-sectional view taken along the line Ixe2x80x94I of FIG. 1.
Referring to FIGS. 1 and 2, gate electrodes 17 having gate oxide films 15 disposed on a p-type semiconductor substrate 11 having device isolation films 13 defining active regions 12, and source/drain regions 19 disposed on the semiconductor substrate 11 at both sides of the gate electrode 17 are illustrated.
The active regions 12 are spaced apart by a predetermined distance from one another in horizontal direction, and alternately arranged in vertical direction. Word lines which are the line-type gate electrodes 17 are spaced apart by a predetermined distance in horizontal direction, and cross the active region 12 at two points.
Since the gate electrode 17 is line-type gate electrode, the gate electrode 17 overlaps an end portion of the active region 12 shown as xe2x80x98Axe2x80x99 in FIG. 1, as well as the two point where the gate electrode 17 cross the active region 12. The overlapping generates Gate Induced Drain Leakage(xe2x80x9cGIDLxe2x80x9d) due to a voltage difference between the word line and the source/drain region, which leads to loss of charges stored in a capacitor, thereby degrading the refresh characteristics of the device.
It is an object of the present invention to provide a method for forming word line of semiconductor device wherein a lower portion of the word line on the channel region is a I-type and a upper portion of the word line is a line-type so that the overlap of the end of the active region and the word line is prevented to reduce GIDL and to improve characteristics, yield and reliability of the device.
In order to achieve the above object of the present invention, a method for forming word line of semiconductor device, comprising the steps of: (a) forming a sacrificial insulation film on a semiconductor substrate including a device isolation film defining an active region; (b) selectively etching the sacrificial insulation film to form an I-type sacrificial insulation film pattern on a predetermined region of the active region where a channel region is to be formed; (c) forming a source/drain region on the semiconductor substrate at both sides of the sacrificial insulation film pattern; (d) forming a first interlayer insulation film on the entire surface; (e) planarizing the first interlayer insulation film to expose a top surface of the sacrificial insulation film pattern; (f) sequentially forming a insulation film and a second interlayer insulation film on the entire surface; (g) etching the second interlayer insulation film and insulation film using a word line mask; (h) removing the sacrificial insulation film pattern to expose the semiconductor substrate; (i) growing a gate oxide film on the exposed portion of the semiconductor substrate; (j) forming a conductive layer on the entire surface; and (k) planarizing the conductive layer to expose the second interlayer insulation film is provided.